Hi, I’m trying to sync multiple OV9281 modules using hardware trigger with an external signal. The setup is UC-599 (OV9281 module) on a UC-593 Rev C USB3 Camera Shield. I followed the guide at Redirecting... With the external trigger applied, I can only adjust the frame rate up to 23 fps. If I set the external trigger frequency above 23 fps, the capture frequency stays at 23 fps, even though the guide says it should go up to 120 fps. Also, several OV9281 modules don’t seem to lock to the trigger, each one keeps running at its own frame rate. Is there a specific OV9281 setting required for trigger sync?
Thanks for the details. I tested the same accessory configuration here and in external trigger mode I can reach 120 fps with the default settings, so the hardware path is capable of it. One thing I noticed is that the exposure ends up very short and the picture is quite dark at that rate. I also captured the waveform of the external trigger signal and it looks fine. That makes me think the 23 fps cap on your side is likely configuration-related rather than a hard hardware limit. Can you share your USB shield board revision, the USB test software version, and the config file you’re using so we can duplicate the test?
Just to recap what I’m seeing: I’ve been following the hardware trigger external signal guide for the OV9281, but the frame rate can only be adjusted up to 23 fps. Above that trigger frequency, the capture stays at 23 fps, and the modules still run independently instead of locking together. I’ll get the shield revision and software version together. In the meantime, can you tell me which USB test software and config you used to hit 120 fps so I can replicate it exactly?
Sure. The test software I used is the Windows USBTest release from GitHub: ArduCAM_USB_Camera_Shield/Windows/GUI/USBTest/x64/Release at master · ArduCAM/ArduCAM_USB_Camera_Shield · GitHub I’ve also sent you the exact configuration file through a private message. Please check your messages, load that config, and try the external trigger test again at 120 fps.
Quick update while I’m still digging into the 23 fps cap. I’ve run into a separate but related issue: when an event lasts only a fraction of a frame, the OV9281 module sends out two or three frames of data for that single event. I need a single frame output for a single frame event. Any idea what causes that and if there’s a workaround? Same setup, UC-599 on UC-593 Rev C.
Can you elaborate a bit on the multi-frame output? I want to make sure I understand the behavior. You have a short event, sub-frame duration, and the camera outputs that same event across two or three frames? Is the event happening at the start of the trigger period or during the exposure? How are you triggering and reading the frames?
Closing the loop on that one, it’s resolved now. The problem was that an event in frame 0 was showing up in frame 1, frame 2, and frame 3. It turned out the exposure wasn’t set correctly, which caused multi-frame exposure. Fixing the exposure made it output a single frame per event.
Good to hear. So the root cause was the exposure setting. Incorrect exposure led to multi-frame exposure, and once it was set correctly the module produces one frame per event. That also matches the short and dark image behavior I saw at 120 fps, exposure has to be tuned carefully in external trigger mode.
One more finding from further testing on the OV9281 modules: when the exposure time is set to more than 70% of the frame period, an event that occurs within one frame gets reported across two to three frames again. For example, an event in frame 0 shows image data in frame 1, frame 2, and sometimes frame 3. This causes image blurring. Is that expected behavior for this sensor?
Thanks for the detail. Based on everything so far, the multi-frame output issue was exposure-related: correcting the exposure gives a single frame per event, and keeping exposure below roughly 70% of the frame period appears to be the current workaround to avoid the blurring and multi-frame reporting. For the original 23 fps cap, our reference config reaches 120 fps in external trigger mode, so that still looks like a configuration or settings mismatch. If you can share the shield revision, USB test software version, and the actual config you’re using, I can compare them against the reference setup.